1. Field of the Invention
This invention relates to a composition of matter and a method of producing the same and is particularly directed to improved solid propellant NF.sub.3 -F.sub.2 gas generators and high detonation pressure explosives.
2. Description of Prior Art
NF.sub.4.sup.+ salts are the key ingredients for solid propellant NF.sub.3 --F.sub.2 gas generators, as shown by D. Pilipovich in U.S. Pat. No. 3,963,542. These propellants consist of a highly over-oxidized grain using NF.sub.4.sup.+ salts as the oxidizer. Burning these propellants with a small amount of fuel, such as aluminum, powder, generates sufficient heat to thermally dissociate the bulk of the oxidizer. This is shown in NF.sub.4 BF.sub.4 in the following equation: EQU NF.sub.4 BF.sub.4 .fwdarw.NF.sub.3 +F.sub.2 +BF.sub.3
As can be seen from the equation the gaseous combustion products contain the volatile Lewis acid BF.sub.3. This disadvantage of a volatile Lewis acid by-product is shared by many of the previously known NF.sub.4.sup.+ compositions. These volatile Lewis acids possess a relatively high-molecular weight and a low .gamma. value (.gamma.=C.sub.pi /C.sub.vi), relative to the preferred diluent helium and frequently act as a deactivator for the chemical HF-DF laser. Consequently, these volatile Lewis acids must be removed from the generated gas prior to its use in an efficient chemical laser. Based on the state of the art, this is achieved by adding a clinker forming agent, such as KF, to the solid propellant formulation. The function of this additive serves to convert the volatile Lewis acid, such as BF.sub.3, to a non-volatile salt as shown by the following equation: EQU KF+BF.sub.3 .fwdarw.KBF.sub.4
In addition, several NF.sub.4.sup.+ compositions are known which are based on self-clinkering NF.sub.4.sup.+ salts, as shown by K. O. Christe et al in U.S. Pat. No. 4,172,884. The theoretical fluorine yields achievable with the presently known NF.sub.4.sup.+ salts are summarized in Table 1.
TABLE 1 ______________________________________ Theoretical Fluorine Yields (in the form of NF.sub.3 and F.sub.2) of Presently Known NF.sub.4.sup.+ Salts Before Burning. THEORETICAL F, RANK SYSTEM WT. PERCENT ______________________________________ 1 (NF.sub.4).sub.2 NiF.sub.6 64.6 2 (NF.sub.4).sub.2 SnF.sub.6 46.0 3 (NF.sub.4).sub.2 TiF.sub.6.2.4KF 39.5 4 NF.sub.4 BF.sub.4.1.2KF 38.6 5 (NF.sub.4).sub.2 GeF.sub.6.2.4KF 37.6 6 NF.sub.4 SnF.sub.5 31.3 7 NF.sub.4 PF.sub.6.1.2KF 31.2 8 NF.sub.4 GeF.sub.5.1.2KF 29.0 9 NF.sub.4 AsF.sub.6.12KF 27.3 10 NF.sub.4 SbF.sub.6.1.2KF 24.0 11 NF.sub.4 BiF.sub.6.1.2 KF 19.7 ______________________________________
As can be seen from Table 1, the self-clinkering (NF.sub.4).sub.2 NiF.sub.6 salt gives by far the highest fluorine yield. Unfortunately, the thermal stability of (NF.sub.4).sub.2 NiF.sub.6 (See: K. O. Christe, Inorg. Chem 16, 2238,1977) is insufficient to pass the requirements of long term stability tests.
Another potential application for energetic NF.sub.4.sup.+ salts is their use in high detonation pressure explosives as disclosed in a recently issued patent titled: "High Detonation Pressure Explosives", (for additional information see U.S. Pat. No. 4,207,124, dated June 10, 1980, by Karl O. Christe, one of the co-inventors of the instant invention).
Again, the most energetic NF.sub.4.sup.+ salt, i.e. (NF.sub.4).sub.2 NiF.sub.6, has the major drawback of insufficient thermal stability to meet long term storability requirements.
The above discussion demonstrates that the prior art provided either a high performing NF.sub.4.sup.+ salt of insufficient thermal stability or low performing NF.sub.4.sup.+ salts of sufficient thermal stability. However, an NF.sub.4.sup.+ salt combining both high energy and good thermal stability has previously been unknown.
Accordingly, it is an object of the present invention to provide a high performing NF.sub.4.sup.+ salt of a thermal stability sufficient to meet long term stability requirements.
Another object of the present invention is to provide a process for the production of such a high performing stable NF.sub.4.sup.+ salt.